butter

                                  BUTTER

i. Definition

Butter is the product obtained from cow or buffalo milk or a combination thereof or from curd with or without the addition of any preservatives including common salt, any added colouring matter or flavouring agents. It shall be free from other animal fat and shall contain not less than 76 per cent of milk fat by weight.

ii. Classification

Butter may broadly be classified into four groups:

Butter can be classified on the basis of type of cream, manufacturing process and ripening process etc. as listed below:

a) Sweet cream butter - is the butter made from non-acidified cream with a pH of e” 6.4 or acidity lower than 0.20% L.A.

b) Sour cream butter - is the butter made from cream acidified by bacterial fermentation to a pH d” 5.1 or acidity more than 0.20% L. A.

c) Mildly acidified butter - is the butter made from partially acidified cream with a pH d” 5.2 – 6.3 (0.16-0.20% L.A.)

d) Pasteurized cream butter - is the butter made usually from pasteurized sweet cream. It possesses usually milder flavour than that made from similar cream but not pasteurized.

e) Ripened cream butter - is the butter made from cream in which a pleasant and delicate aroma known as ‘real butter flavour’ has been developed by ripening before churning. Ripening is a process in which the cream is inoculated with a butter culture and allowed to stay overnight at controlled temperature.During this period the titratable acidity of cream increases and the pH varies in the range of 4.4- 5.6.

f) Un-ripened cream butter - is the butter made from un-ripened or fresh cream. The flavour of such butter is usually mild.

g) Salted butter - is the butter made by the addition of a maximum 3.0 per cent salt after the buttermilk has been drained off. The salt added, enhances the taste and prolongs the preservation of the product by inhibiting the growth of microorganisms. It is more often referred as ‘table butter’

h) Unsalted butter : It contains no added salt. It is also referred to as ‘sweet butter’ or ‘cooking butter’. It is preferred for use in cakes, pastry and ghee making.

i) Fresh butter : Butter, which has not undergone for cold storage is referred as‘fresh butter’. Usually, it is not kept for more than 3 weeks.

j) Cold storage butter : Butter, which has been stored at a temperature of about–18°C (O°F) for some time is cold storage butter. Generally, it is one to six months old when offered for retail trade.

k) Dairy butter (USA) : It is usually made, from un-pasteurized sour cream,which has not been standardized for acidity. Dairy butter generally has a sour flavour due to the high acid content of the cream.

l) Creamery butter : Made in a creamery or dairy factory. It is more uniform in quality than ‘dairy butter’

Standards

Regulatory bodies such as Prevention of Food Adulteration Act, Bureau of Indian Standards etc., have laid quality standards for butter so that a customer gets a uniform and quality product from the market.

 

i. Prevention of Food Adulteration (PFA) Act

According to the Prevention of Food Adulteration Rules (1976), Table/Creamery butter means the product obtained from cow or buffalo milk or a combination thereof or from cream or curd obtained from cow or buffalo milk or a combination thereof with or without the addition of common salt and annatto or carotene as colouring matter. It shall be free from animal fat, wax and mineral oils, vegetable oils and fats. No preservative except common salt and no colouring matter except carotene or annatto may be added. It shall contain not less than 80 per cent by weight of milk fat, not more than 1.5 per cent by weight of curd, and not more than 3.0 per cent by weight of common salt. Diacetyl may be added as flavouring agent but shall not exceed 4.0 parts per million.

 

ii. Bureau of Indian Standards (BIS) for Butter

Table butter means the product made from pasteurized cream obtained from pasteurized milk of cow or buffalo or a combination thereof with or without ripening with the use of standard lactic culture, addition of common salt, annatto or carotene as the colouring matter and diacetyl as flavouring agent. BIS specifications for butter are given in the Table 

i. Composition

Butter consists of milk fat, non-fat-constituents and water. The water is uniformly dispersed as fine droplets in butter so that it looks dry. Main constituent of butter is milk fat comprising glycerol and fatty acids. Milk fat is comprised mostly of triglycerides, with small amounts of mono and diglycerides, phospholipids, glycolipids and lipoproteins. The triglycerides (98% of milk fat) are of diverse composition with respect to their component fatty acids, approximately 40% of which are unsaturated.

Butter melts at about 35°C (96 °F) and re-solidifies at 23°C (73°F). The firmness of butterfat varies with the proportion of saturated and unsaturated fatty acids,chain length, degree of un-saturation (mono or poly), and position of the fatty acids on the glycerol molecule. The change in butter softness is associated with the changes in fatty acid and triglyceride structure of the milk fat. On an average,butter contains about 50.5% saturated fatty acids, 23.5% mono-unsaturated fatty acids, 3.0% poly-unsaturated fatty acids and 0.22% cholesterol.

Creamery Butter Method

This is the standard method adopted by organized dairies. In this method unsalted creamery butter or white butter or cooking butter is used a raw material for ghee making. A typical plant assembly for the creamery butter method comprises the following units. (1) a cream separator (2) butter churn (3) butter melting outfits (4) steam-jacketed, stainless steel ghee kettle with agitator and process controls (5) ghee filtration devices, such as disc filters or oil clarifier (6) storage tanks for cream, butter and ghee (7) pumps and pipelines interconnecting these facilities (8) crystallization tanks and (9) product filling and packaging lines.

First, the butter mass is melted at 60oC. The molten butter is pumped into the ghee boiler. Alternatively, solid butter may also be transferred manually to ghee kettle.The steam pressure is increased slowly to raise the temperature of butter to 90oC.This temperature remains constant as long as the moisture is being driven off. The scum, which collects on the top surface of the product may be removed from time to time with the help of a perforated ladle. The temperature gradually rises and the heating at the last stage is carefully controlled. The end-point shows the disappearance of effervescence, appearance of finer air bubbles on the surface of fat, and browning of the curd particles. At this stage, the typical ghee aroma is also produced. The final temperature of clarification is adjusted less than 110oC. Heating beyond this temperature will generate a marked ‘cooked’ flavour. The ghee is then pumped, via an oil filter or clarifier, into crystallization tank, which are cooled by re-circulating water at 60oC. The ghee is then packed in suitable containers.

Advantages

• This method produces ghee of highly consistent quality.
• Quantity of ghee residue is very less, hence less fat losses.
• Less space is required for storage of cooking butter, the raw material for this method.
• Energy requirement are lower than direct cream and indigenous methods.
• Longer keeping quality than indigenous method

Disadvantages

The flavour of ghee prepared by creamery butter method is criticized to be either flat/bland or cooked, particularly to the consumers who are habitual of using village ghee made by traditional method. The granulation in ghee is also poor as compared with the earlier discussed method.

iv. Pre-stratification Method

The ghee boiler in pre-stratification method is slightly modified. A faucet is provided at lower end (almost at side of bottom) of the boiler to remove most of the buttermilk (moisture and SNF). In this method, white butter is heated at a temperature of about 80oC and left undisturbed for about 30 minutes at this temperature. The melted butter stratifies into three layers, viz., a top layer of floating denatured curd particles, a centre layer of fat, and a bottom layer of buttermilk. This separation of butter into layers is called as pre-stratification. The bottom layer of buttermilk contains 60-70 per cent of milk solids-no-fat and also over 80 per cent of moisture originally present in the butter. The buttermilk is mechanically removed without disturbing the top and middle layers. Afterwards, the temperature of remaining two upper layers is raised to the usual clarifying temperature of about 110oC and ghee prepared as discussed above for creamery butter method.

Advantages

• Economy in fuel consumption to an extent of 60 per cent as compared with direct clarification.
• The acidity of ghee is less, which results into longer keeping quality.
• Exposure to high temperature for lesser time.
• The amount of residue formation is reduced.

Disadvantages

It is essentially a batch method unsuitable for continuous production of ghee.
The flavour of ghee is very mild or rather flat.

v. Continuous Method

The batch methods for making ghee discussed earlier are highly suitable for small and medium scale production of ghee. With the increase in demand and scope for export of ghee, some very large organized dairies prefer to adopt a continuous ghee making methods. Some of the problems associated with the current batch methods of ghee making are:

• Unsuitable for large-scale production.
• High-energy consumption.
• Excessive strain and fatigue on the operators.
• Product exposed to the environment.
• Cleaning of equipment is done manually.

All the limitations of the conventional batch methods given above are obviated by continuous ghee making plants. These systems work on the basis of two principles,viz. (a) moisture evaporation from cream/butter using thin film scraped surface heat exchanger (TSSHE) and (b) de-emulsification of cream using high speed clarifixator and oil concentrator followed by moisture evaporation. The design, function and special feature of continuous ghee making units are discussed below:

TSSHE for continuous ghee making: The white or cooking butter from continuous butter melter is pumped in balance tank where it is kept agitated by means of agitator to maintain the homogeneity of molten butter. Then the butter is pumped to the TSSHE. The flow rate of molten butter is indicated by a rotameter and controlled with a value provided on the inlet line. The centrifugal action of the rotor blade make the molten butter spread uniformly in form of a film on the heating surface of the SSHE. Steam is admitted at regulated rate into the jacket of SSHE. The rate of evaporation of water from the butter film is very fast due to turbulence caused by the action of rotating blade. The speed of rotor blade is controlled by a motor drive. The vapour is removed through the outlet provided at the top of the SSHE and can be used for heating the butter in balance tank, thus economizing the steam consumption. The temperatures of molten butter and ghee are indicated by thermometers and adjusted by controlled steam supply with valves. Ghee is collected continuously in the ghee tank. The residue is separated from ghee by the oil clarifier. Residue free ghee is finally transferred to packaging line/tank.

Cream de-emulsification method: This method of continuous ghee making is based on the principle of de-emulsification of fat in cream from oil-in-water phase to water-in-oil phase. In this process milk is separated into cream of 40% fat using a centrifugal cream separator. This cream is converted into plastic cream of 80% fat in a clarifixator and then further concentrated in a concentrator, which work under centrifugal force. The de-emulsification of fat is done mechanically in the clarifixator and concentrator. Scraped surface heat exchanger is used to generate flavour and remove most of the moisture from fat concentrate. The traces of moisture left in ghee are removed in a vapour separator and the ghee residue removed by a oil clarifier. The flow diagram of the process is shown in below.

Over Run

The weight of butter obtained from a given lot of cream is always more than the amount of fat present in cream. The amount of butter, which exceeds the amount of fat present in cream is called overrun. In other words, it may be defined as the increase in the amount of butter made from a given amount of fat. It is usually expressed as percentage overrun. The presence of moisture, curd, salt, air, etc., in butter increases the amount of butter. It is a source of profit to the manufacturer and also helps to check the efficiency of the working of the plant. There are several types of overrun which include

i) Theoretical: Theoretically, maximum obtainable overrun in butter is 25% because 80 kg fat yields 100 kg of butter as per PFA standard.

ii) Compositional: It is based on the composition of butter and varies according to the fat content in butter.

iii) Factory: It is calculated on the basis of total packed butter and total fat received in the factory for butter-making.

iv) Churn: This is calculated for a particular type of churn

The formula used for the calculation of Theoretical over-run is given below:

Per cent Over-run (% OR) = (B - F)/F

Where,

B = Quantity of butter made (kg)
F = Fat in churn (kg)

Factors Influencing Over-run:

The following factors affect the over-run in butter:
Inaccuracy in weighing of milk, cream or butter;

Inaccuracy in fat testing of the samples of milk, cream or butter;
Fat losses in skim milk and butter milk;
Fluctuation in fat content of butter;

Weight allowance in butter packages;
Handling losses.

                                Butter Oil

It may be defined as clarified butterfat and normally having bland or flat flavour. The grains are either absent or under developed in it.

Compostion of Ghee and Butter Oil

Composition of Ghee: Ghee and butter oil as given in definition, are essentially the isolated fats of milk, which constitutes about 99.5%. The other constituents of varied nature are present in solution in the fat. Moisture is always present because it cannot be completely removed merely by boiling. All fats, including ghee, also dissolve gases present in the atmosphere, like nitrogen, oxygen and carbon dioxide.Some 0.5% of the material present in ghee is collectively known as unsponifiable matter, since on boiling with alkali, it is not converted into soap, and can be extracted with solvents like ether. This unsponifiable matter is a complex mixture of substances like sterols, vitamins and hydrocarbons, which though present in small amounts are of considerable significance. In addition to fat and unsponifiable matter, ghee also contain some other trace constituents. The presence and proportions of these trace compounds, like hydroperoxides, aldehydes, ketones, phospholipids, proteins, sugars and trace minerals, depend on the past history of ghee. The general composition of ghee obtained from cow and buffalo milks is given in the Table

Nutritive Value of Butter Oil

Ghee and butter oil, being pure butterfat, are concentrated source of energy, supplying nine calories per gram as against four calories supplied by one gram each of pure source of either protein or carbohydrate.

Ghee particularly that prepared by traditional milk fermentation route, has good medicinal value. Ghee is a carrier of fat-soluble vitamins, A, D, E and K, which our body needs in very small quantities but cannot make for itself. These vitamins perform many essential functions. Similarly, the essential fatty acids, which cannot be synthesized in our body are also supplied by ghee. Ghee has been recognized as Indian medicine in Ayurveda. It is used in various disorders both externally as well as internally. There are about 55-60 medicated ghee types reported in Ayurvedic literature and they are used for treatment of various diseases. Medicated ghee is always prepared with selective fortification with herbs, so as to acquire all the required fat-soluble therapeutical components of the herbs. Some of the examples of medicated ghee are: Arjima ghrit, Ashok ghrit, Dhanvantar ghrit, Amruta ghrit, etc. Emerging scientific findings indicate that ghee contains several components such as conjugated linoleic acid (CLA), sphingomylein, butyric acid, myristic acid and vitamin A, which have potential to inhibit the development of cancer. In fact,ghee is the richest natural dietary source of CLA, which has shown to inhibit carcinogenesis of colour, mammary tissue, skin and fore stomach. CLA present in ghee is also known to have serum cholesterol lowering properties. Compared to Ghee, Butter Oil and Low Fat Spreads other fats and oils, milk fat (ghee) is easily digestible. The digestibility of ghee and butter oil is 99% while that of natural palm oil is 91%. Also ghee is rich in short and medium chain fatty acids, which are more easily absorbed than long chain fatty acids

Methods of Manufacture of Butter oil

The following methods are used for manufacture of butter oil.

•  Evaporation under vacuum.
•  Decantation of molten butter.
•  Centrifugal separation of butterfat followed by vacuum drying.
•  Direct from cream by de-emulsification and centrifugation.

First three methods make use of butter as raw material.

i. Evaporation of Butter under Vacuum

This is a batch process and carried out normally under vacuum. Molten butter is taken in a vacuum pan and boiled under vacuum until moisture is completely removed.SNF (residue) is subsequently removed by physical or mechanical methods. Neither the efficiency of the process nor product quality are satisfactory in this method.

ii. Decantation

It is like pre-stratification method of ghee making, i.e. butter is heated to about 80oC, left undisturbed for some time. This results in the formation of three layers,viz. top scum, middle fat and bottom serum. The top layer and bottom layers are discarded and middle fat layer is separated and used as Butter oil. Fat recovery is less, hence method is uneconomical, especially when employed on a large scale.

iii. Centrifugal Separation followed by Vacuum Drying

This is a continuous method and produces a product of high quality. Invariably butter oil is prepared by this method. Butter (unsalted) is dumped in the butter melter, which is a vertical jacketed stainless steel tank fitted with an agitator. Hard butter is cut into small pieces before heating.Then steam valve is opened and agitator is started. The temperature of water in tipping tank is adjusted to 77 – 79oC with the help of steam and hot water is allowed to pass through the oil separator. Subsequently molten butter is allowed to go to tipping tank and oil separator. The rate of flow is so adjusted that there is no overflowing. The melt is separated into oil and serum.

The oil flows into the float controlled balance tank and from there into the vacuum pan due to suction. Here it is heated at 56-63oC under a vacuum of 56-62 cm Hg.All the moisture is removed from all the oil at this stage. At the end of operation,the vacuum is released and butter oil allowed to flow by gravity into the receiving kettle for subsequent cooling, packaging and storage.

iv. Directly from Cream by De-emulsification and Centrifugal Separation

The process utilizes the principle of de-emulsification of cream used in various continuous butter making processes. De-emulsified fat may then be melted and clarified by centrifuging and vacuum heating.